Mayday (2013) s17e05 Episode Script
Lethal Turn
Come on, climb! Climb! Climb! NARRATOR: An Airbus A300 veers fatally off-course.
No! No! No! It was the biggest human loss in Indonesian history.
It really was overwhelming.
These are two pieces we need to find.
The task was to find the black box.
As investigators begin to examine the evidence COMMS: Indonesia 152, turn right heading 0-4-6.
Here, right on course.
.
.
each new clue is more perplexing than the last.
- That's go-around power.
- We cannot figure it out.
The impact point was nowhere near where we would expect the aircraft to be.
Where did they think they were going? We just didn't understand that.
## (PACEY MUSIC) NARRATOR: There are 222 passengers on-board Garuda Indonesia flight 152.
They're on their way to the city of Medan on the Indonesian island of Sumatra.
Let's stay on autopilot as long as we can.
Yes, sir.
Captain Rahmo Wiyogo has been flying in Indonesia for nearly 20 years.
He's extremely familiar with today's flight path.
For missed approach, climb straight ahead to 2,500 and contact ATC.
You don't have to write this down.
Just relax.
Yes.
OK, sir.
Tata Zuwaldi has only recently upgraded from flight engineer to first officer.
The plane they're flying is an Airbus A300, one of the most reliable commercial airliners in the sky.
Flight 152 left the Indonesian capital of Jakarta nearly 90 minutes ago.
Headed northwest, it is expected to arrive at its destination in about half an hour.
MALE VOICE: Surface winds calm.
Visibility 400m.
An automatic weather report alerts the crew to one factor about their flight that's not routine.
Present weather - smoke.
Forest fires in Sumatra have sent a thick blanket of smoke across all of Southeast Asia.
It's wreaking havoc on people's health and on air traffic.
Smoke is limiting visibility to a degree that would make the descent and the approach really quite difficult.
Not impossible but really quite difficult.
The cabin crew of Flight 152 begin preparing for the upcoming descent.
On the ground, it's a busy afternoon for Medan air-traffic controllers.
Indonesia 152 requesting descent clearance.
They're handling flights from several domestic airlines, including Merpati, Bouraq and Garuda Indonesia.
Confirming descent to flight level 1-4-0.
The controller clears Garuda 152 to begin its descent.
Descending to flight level 1-4-0, Indonesia 152.
Medan Airport has just one runway.
Right now the controller has a Bouraq Airlines flight ready to take off.
He needs to slow the approaching Garuda flight until that plane clears the runway.
Indonesia 152, descend to 3,000ft for runway 0-5.
Reduce speed 2-2-0.
Reduce speed to 220 knots, Indonesia 152.
Seatbelt.
No smoking.
Less than 15 minutes from the airport, flight 152 descends through 10,000ft.
It's smoky here below 10,000.
Oh, yeah.
The pilot would never have been able to get any external visual cues.
He would have been flying entirely on instruments.
The reduced visibility puts added pressure on the controllers.
If there is smoke all the way down to the ground, the controller knows the pilot is going to encounter problems.
They're gonna need all the help they can get and the controlling should be very accurate.
The captain adjusts the power to his engines.
COMMS:: Merpati 152, turn left heading 2-4-0 to intercept runway 0-5.
Number one always lags behind a bit so keep an eye on it for me.
OK.
Indonesia 152, do you read? Indonesia 152.
Say again? OK.
Ah, turn left heading 2-4-0 2-3-5 now to intercept runway 0-5.
Roger, left heading 2-3-5, Indonesia 152.
The plane below has now taken off.
The runway is clear.
Bouraq 683, turn left heading 1-2-0.
Indonesia 152, traffic clear.
Descend to 2,000ft.
Descending to 2,000ft, Indonesia 152.
If it wasn't for the heavy smoke, passengers would be able to see the ground by now.
They had very limited visibility.
Anybody who's driven a car in fog will know what I'm talking about.
Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
- Flaps 8.
- Speed check.
Flaps 8.
The cockpit is hot.
See what you can do.
It's so hot.
It's set to cool, sir.
It should be fine.
Any second now, the controller expects to see flight 152 turn onto final approach.
What? The Airbus has somehow become dangerously close to the ground.
Come on, climb! Climb! Climb! The crew struggles to raise the plane's nose and gain altitude.
But the 130-tonne jet takes time to respond.
Time they don't have.
No.
No! No! No! No! (BLEEP) Locals rush to the crash site 17 miles from Medan Airport.
It's soon clear there's nothing they can do to help.
All 234 people onboard the flight are dead.
This is the deadliest aviation accident in Indonesia's history.
The entire nation wants answers.
We should come to the answer on not only what happened, how it happened, but also why it happened.
Investigators soon join the throngs of police and locals already at the crash site.
Let's see how far back this wreckage goes.
Santoso Sayogo is a key member of the investigative team, and the accident has affected him personally.
I knew both the captain and first officer for a long, long time.
When you found out that your two friends was the victim of the accident, it's quite a shocking experience.
Santoso! We'll need to secure the site somehow.
The Air Accidents Investigation Branch sends Rob Carter to assist with the investigation.
The site was chaotic.
There were lots of people around, some in uniform but it didn't seem like very many.
There was no overall control.
Lots of people doing different things, very little that seemed to be related to accident investigation.
The smell was almost overpowering at that stage.
Coupled with the heat and the humidity and the pollution it really was overwhelming.
The chaotic scene is an immediate concern for Carter.
He's worried the lack of security could compromise the investigation.
A tremendous number of local people were going over the wreckage in different ways and they were carrying pieces away.
We worried that they might be carrying away bits of aircraft, which we'd be really interested in.
If authorities can't gain control of the site and protect valuable evidence, the truth about what happened to Garuda Indonesia flight 152 may never be known.
OK, good.
- Left engine was found here.
- Excellent.
The wreckage from flight 152 lies 17 miles southwest of Medan Airport.
The compact nature of the crash zone tells investigators that the plane was in one piece when it hit the ground.
It looked as if we had most of, if not all, of the aircraft within an area 120x80m.
That's pretty compact.
The wreckage tells investigators something else as well, something they can't explain.
The debris field shows that the plane was flying away from the airport when it slammed into a hillside southwest of the runway.
It's exactly opposite from the direction they should have been flying.
One of the things that seemed so strange was where the impact point was.
It was nowhere near where we would expect the aircraft to be for the proper sort of approach into the airport.
We just didn't understand that.
These are two pieces we need to find.
They hope the plane's flight recorders can help clear up the mystery.
They should be in this area here.
OK, let's go.
Our principle is find the black box, and the clues and the evidence are there.
Investigators fear the boxes may have been carried off by looters.
They recruit hundreds of local people to search for them.
ROBERT CARTER: We were really looking very strongly for the cockpit voice recorder, flight data recorder, really to fill in any sort of detail on how this had happened.
At the same time, they gather information from the air-traffic controller, the last person to have communicated with flight 152.
They approached from the southeast.
I was trying to bring them in this way, a left turn and a right turn that gets them into runway 0-5.
The controller suspects the captain somehow misinterpreted his instructions and missed the final turn.
He didn't understand which way to turn.
He made a left turn here instead.
But without the cockpit recording and the flight data, it's impossible to say why the plane turned the wrong way.
Perhaps there was a mechanical failure or some other last-minute crisis.
We could not determine why the captain make the aircraft turning to the left.
This is a very interesting.
This is It's a big puzzle.
With no sign of the black boxes, investigators gather air-traffic recordings made in the tower.
It's hoped they can shed some light on why the plane turned away from the airport instead of towards it.
We were still wondering whether it could be some sort of systems failure, possibly even some sort of mild structural failure, some distracting aspect for the pilots.
It really left that pretty wide open.
Roll tape.
COMMS: Confirming descent to flight level 1-4-0.
NARRATOR: The air-traffic recordings capture only the radio calls between the pilots and the controller.
Indonesia 152, descend to 3,000ft for runway 0-5.
They're not as helpful as a CVR recording, which would reveal all sounds and conversation inside the cockpit.
Reduce speed 2-2-0.
He needs to get Bouraq 683 airborne.
But investigators listen closely for any clue as to why the A300 veered so badly off course.
At first, the communication seems completely normal.
Merpati 152, turn left heading 2-4-0 to intercept runway 0-5 from the right side.
But then, the controller uses the wrong call sign.
You have Merpati 152, and now he's got Garuda 152.
Records show that earlier in the day, the controller was talking to a Merpati flight with the same number, 1-5-2.
It seems that now he's mixed up the two call signs.
Instead of Garuda 152, he said 'Merpati 152'.
The Garuda pilot didn't pick this message up for obvious reasons.
- COMMS: Indonesia 152, do you read? - Indonesia 152.
Say again? Then suddenly the controller realised that he'd given the wrong call sign, so he called up for a second time.
OK.
Uh, turn left heading 2-4-0 2-3-5 now to intercept runway 0-5.
Left heading 2-3-5.
Roger, left heading 2-3-5, Indonesia 152.
NARRATOR: It appears the misunderstanding is quickly cleared up.
The controller says they made that turn.
After the brief moment of confusion, the Garuda flight is exactly where it should be.
On heading 2-1-5, Indonesia 152.
That puts them about here, right on course.
One more right turn and he's lined up with the runway.
Indonesia 152, turn right heading 0-4-6.
There it is.
Clear as day.
Turn right heading 0-4-6, Indonesia 152.
OK, stop there.
They definitely understood "Turn right.
" How the flight went so horribly wrong in the final few moments is baffling.
It's in the exact opposite direction they were told.
Why? The ATC give instruction, "Indonesia 152, turn right onto heading 0-4-6," but the aircraft turned to the left.
At that stage, we do not have any clue at all.
Investigators need the CVR if they hope to figure out what exactly went on in the cockpit of Flight 152.
A week after the crash of Garuda Indonesia flight 152, devastating scenes of loss and suffering underscore the accident's human toll.
Indonesians from all walks of life want to know what caused this deadly tragedy.
They have to be somewhere.
Let's go back to where we started and look again.
Let's go.
Come on.
Let's go.
There's still no sign of the plane's black boxes.
Investigators are beginning to worry that the answers so many people are hoping for may never be found.
We've got to find them.
It was very frustrating not having the cockpit voice recorder and the flight data recorder.
They are really crucial to understanding the subtleties of an aircraft accident.
The terrible conditions at the accident site aren't helping.
At that time, it was rainy season and you can imagine how wet it was and slippery, as well.
Despite the setbacks, the team presses on.
Let's see if we can figure out what this plane was doing.
They collect key pieces of wreckage, including flight instruments from the cockpit.
Soerjanto Tjahjono of the National Transportation Safety Committee hopes those instruments will tell him how the plane was performing.
We could not find the black boxes, so we used anything from the cockpit, like the gauges, any instrument in the cockpit.
Many of the gauges on this version of the Airbus are electronic, which means that when they lose power, they display their final readings like a snapshot in time.
When electrical power goes off, the instrument freezes.
Those readings provide valuable insight into the final moments of flight 152.
There it is.
It looks like 1.
552.
That's go-around power.
They were trying to fly out of trouble.
The engine instruments showed us that the engines were actually at a very high level of thrust at the point that they lost electrical power.
The finding reveals that the pilots saw the danger ahead and tried desperately to get their plane to climb.
The crew had responded by increasing the engine thrust when they realised they were close to the ground.
As the evidence begins to add up, the likelihood of a mechanical failure aboard Garuda 152 looks increasingly remote.
It sure seems like the aircraft was under control.
Putting it all together, the instruments seemed to indicate to us that the aircraft was what we call a 'going concern' when it hit that ridge, that it was some sort of controlled flight into terrain.
'Controlled' means that there's nothing wrong with the aeroplane and yet it ploughs into a mountainside.
It's been 26 days since the crash of flight 152.
Investigators still have no explanation for its mysterious final turns and fatal impact.
But then, they get their first big break.
Well, well, well.
It turns out that the plane's voice and data recorders were not carried off by looters, but they were almost completely hidden from sight in the dense Indonesian forest.
It was a surprise for us to find that the two black box were sitting there for 26 days until we found it in very soft soil and entangled with the root of the falling tree.
Let's hope they hold some answers.
They rush the boxes to a lab where technicians will work to recover cockpit sounds and conversation, along with detailed aircraft performance data.
The long wait for the most crucial evidence is almost over.
We tried to concentrate first on the FDR and try to figure out the flight path of the aircraft.
When investigators plot the newly found data, they see that it finally rules out any chance of a mechanical failure.
So left away from the airport and then a right turn smack into the mountains.
It clearly shows that the pilots deliberately commanded that fatal turn.
Where did they think they were going? Can you bring me the descent profile, please? After we got the FDR, some questions got some answers.
The data also shows that the plane was in a steady descent until it hit a treetop at about 1,500ft.
So, why didn't they level off at 2,000ft? Indonesia 152, traffic clear.
Descend to 2,000ft.
The crew was not cleared to descend any lower than 2,000ft.
They should have held that altitude.
So, here we were, somehow, with the aircraft hitting a tree about 500ft below its last cleared altitude.
That was a real mystery.
Investigators now know the pilots turned in a direction opposite to the controller's instructions and dropped below their assigned altitude.
What they still don't know is why.
They hope the cockpit voice recorder can provide an answer.
Let's start with turn number one here.
COMMS: Indonesia 152 requesting descent clearance.
NARRATOR: For Santoso Sayogo, the job of listening to the recording comes with an extra burden.
I knew both pilots, the captain and the first officer, and I personally can recognise whose voice are coming from the CVR.
It's not easy to listening to the tape.
ATC COMMS: Merpati 152, turn left heading 2-4-0 to intercept runway 0-5 from the right side.
OK, that's the confused call sign.
Number one always lags behind a bit so keep an eye on it for me.
OK.
The tape reveals that the Garuda pilots don't respond to the first instruction because they don't think it's for them.
ATC COMMS: Indonesia 152, do you read? Indonesia 152.
Say again? OK.
Uh, turn left heading 2-4-0 2-3-5 now, to intercept runway 0-5.
NARRATOR: The controller repeats himself.
Roger, left heading 2-3-5, Indonesia 152.
The crew then make the turn as instructed.
Why so far out? So far out? And yet, the recording leaves investigators with a disturbing impression.
152, heading 2-3-5.
Confirm that we are clear of the mountainous area.
He doesn't sound sure of where he is.
There seemed to be some degree of confusion between the pilots and the air-traffic controller as to where the aircraft was.
Confirm, sir.
Continue turning left heading 2-1-5.
They're on course.
A right turn toward the runway is next.
ATC COMMS: Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
They turned left instead.
What investigators hear next makes the left turn even more baffling.
- Flaps 8.
- Speed, check.
Flaps 8.
Even though the crew is turning away from the airport, they're configuring their plane as though heading towards it.
Why would you extend flaps while turning away from the airport? What if he thinks he is turning towards the airport? What if he thinks he's here? He believes he has to turn left to get to the runway.
Feeling he may be close to a breakthrough, Santoso Sayogo reviews the airport approach chart.
The charts lay out what the normal approach is, and the pilots normally expect to fly that.
He discovers that Garuda 152 wasn't on the standard approach.
The standard approach to Medan is from the left side, which involves making a final left turn to line up with the runway.
But because there was an aircraft departing, the Garuda captain was instructed to approach from the right side of the runway, requiring something he wasn't used to - a right turn before landing.
The controller took them in a direction, which was not what they would have expected according to the approach charts.
But there shouldn't really have been a problem with that.
Controllers are supposed to confirm the approach path with the pilots well before they get to the runway.
How could he not have known which approach he was flying? Back to 1:27, please.
ATC COMMS: Merpati 152, turn left heading 2-4-0 to intercept runway 0-5 from the right side.
NARRATOR: As Santoso Sayogo listens again to what he thought was a harmless call-sign mix-up, he suddenly realises that it had major consequences.
Indonesia 152, say again? When the controller repeats the approach instructions, he leaves out a critical detail.
Turn left heading 2-4-02-3-5 now, to intercept runway 0-5.
He didn't repeat which side they were approaching from.
He should have made it clear, "You're not going to come in from the left-hand side of the runway.
You're going to come in from the right-hand side.
" He thinks he's flown past the airport when he's told to make this turn.
He's expecting the next turn to be a left turn but instead, he's told to turn right.
It seems that the captain, still unable to see the ground through the smoke, dials in a left turn out of habit.
It is a tragic error that leads to disaster.
But investigators now wonder, "Why did the first officer not notice his captain's mistake?" Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
First Officer Zuwaldi clearly acknowledges the instruction for a right turn.
Yet seconds later, the plane turns left.
It's almost impossible to understand.
Investigators have established that the captain of Garuda Indonesia flight 152 made a fatal turn after a radio-call mix-up left him with a confused mental picture of the approach he was flying.
The vectors, the directions given them by the air-traffic controller, can create a bit of confusion.
Controllers didn't make it clear enough to the pilots that this was not going to be the standard pattern.
ATC COMMS: Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
NARRATOR: They focus on the words of the first officer in an attempt to understand why he didn't immediately react to the wrong turn.
It's getting hot, isn't it? The cockpit is hot.
See what you can do.
It's so hot! The captain asked the first officer to check the air-conditioning.
The co-pilot turned his eyes upward to the panel where he checked the air-conditioning controls.
The brief distraction diverts the first officer's attention from his instruments at a critical moment.
It's set to cool, sir.
It should be fine.
As a result, the co-pilot missed crucial information from the instruments.
Turn right! He looked back.
He was surprised to find out that the aircraft turning to the left instead turning to the right.
Indonesia 152, confirm turning left or right heading 0-4-6.
ATC COMMS: Turning right, sir.
Sorry, Captain.
Sorry.
Roger, 152.
152, confirm you are turning left now.
We are turning right now.
152, OK.
Continue turning left.
NARRATOR: In all the confusion over which way to turn Turn left? - We are turning right now.
- Oh, god! OK NARRATOR: .
.
valuable seconds are lost.
They're flying straight towards the mountain.
ROBERT CARTER: There were many confusing factors for him.
What? The smoke pollution was certainly one of them.
The confused instructions of air-traffic control.
He did not really have a good mental picture of where the aircraft was and where it was meant to be.
Climb! Climb! Climb! The moment they took the wrong turn, they were doomed.
It was this uncertainty, lack of clarity in the captain's head, which really let this accident happen.
NARRATOR: The recording helps explain how Garuda flight 152 ended up so badly off-course.
But it doesn't answer another critical question.
Indonesia 152, traffic clear.
Descend to 2,000ft.
Descending to 2,000ft, Indonesia 152.
The crew was instructed to descend no lower than 2,000ft and their autopilot should have kept them at that altitude.
They had gone straight through 2,000ft and were heading for 1,500ft, and that was too low.
How did they end up below 2,000ft? Either the autopilot had failed in some way or other, which is unusual, or the crew had input the wrong altitude.
NARRATOR: Unfortunately for investigators, the plane's autopilot system was destroyed in the crash.
This impact was so severe, they could pick up the bits afterwards but they couldn't establish whether there was something wrong with it on the day.
Maintenance records show no history of the autopilot ever failing to maintain proper altitude, so a malfunction seems unlikely.
And a report from Airbus all but eliminates the possibility of autopilot failure.
Engineers calculated that the odds of such a failure are less than one in two billion.
It's almost impossible for it to fail.
Descending to 2,000ft, Indonesia 152.
Investigators suspect the captain made an error while entering his minimum altitude.
It was more probably crew mis-setting than it was autopilot failure.
Indonesia 152, confirm turning left or right heading 0-4-6.
ATC COMMS: Turning right, sir.
Sorry, Captain.
Sorry.
Roger, 152.
As the aircraft passes below its target altitude of 2,000ft ATC COMMS: 152, confirm you are turning left now.
- We are turning right now.
- .
.
the pilots are engaged in a confusing conversation about which direction to turn.
152, OK.
Continue turning left.
Turn left? We're turning right now.
They were so preoccupied with their turn, they didn't notice their altitude.
Both pilots didn't realise that the aircraft already left 2,000ft.
By the time the first officer does notice the dangerously low altitude Uh, we're descending.
What? .
.
it's too late.
The quality of their monitoring of their instruments was not up to scratch.
Come on, climb! Climb! Climb! And that's why they got too low and they hit the high ground.
It's finally clear how Garuda Indonesia flight 152 dropped below the minimum safe altitude.
But there are still important questions to answer.
ATC COMMS: Indonesia 152, traffic clear.
Descend to 2,000ft.
The controller in Medan had a read-out of flight 152's altitude and direction.
If he'd recognised the danger and warned the crew, hundreds of lives could have been saved.
Why didn't that happen? ATC COMMS: Descending to 2,000ft, Indonesia 152.
Investigators need to understand why the Medan controller never warned the Garuda pilots of impending danger.
They pore over the technical specifications for Medan's radar system.
Most advanced radar systems refresh every five seconds.
But they soon discover that the radar in Medan is far from advanced.
The radar only refreshed every 12 seconds.
That means the controller only gets an updated picture of where the aeroplane is every 12 seconds.
152, confirm you are turning left now.
- We are turning right now.
- A lot can happen in 12 seconds.
So when the pilot turned in completely the wrong direction - Continue turning left.
- .
.
the controller was not seeing what the pilot was doing Oh, god.
.
.
until it was getting to be too late.
Investigators are close to fully understanding the tragic crash of flight 152.
There's just one last mystery to solve.
Most commercial jets have a cockpit alarm that sounds when the plane flies too close to terrain.
AUTOMATED VOICE: Terrain.
Terrain.
Pull up.
Pull up.
NARRATOR: It's called the Ground Proximity Warning System, a loud automated voice alerting pilots to danger.
One of the big questions for us was, "Why did the accident happen when the aircraft was equipped with a Ground Proximity Warning System?" According to the flight data recorder, the GPWS on flight 152 was triggered five times.
The crew should have heard the first warning 37 seconds before impact.
But when they check the cockpit recording, they only hear the voice alarm once.
Pull up.
Pull up.
Pull up.
And it comes just four seconds before impact.
Something's not right.
They send the tape to an audio lab where sound technicians enhance the quality of the recording.
Listening to the enhanced tape, investigators make a stunning discovery.
Pull up.
Pull up.
Pull up.
The alert, "Pull up, pull up," is not the sound of an automated voice.
It's definitely Zuwaldi, the first officer.
Then we realised the recorded of, "Pull up, pull up," wasn't from the GPWS but it was from one of my friend.
It can mean only thing.
We knew that the GPWS was not working.
It's ultimately revealed that there is a flaw in the GPWS that prevents a warning from sounding when planes are descending over certain types of mountainous terrain.
The GPWS never give the warning to the pilot.
Over the years, GPWS has saved countless lives.
It was sad in this case that those lives weren't saved, and the modern systems, enhanced GPWS, certainly would have worked way better.
Investigators have finally uncovered the tragic series of events that led to the loss of 234 lives.
It all starts with a controller who confuses one call sign for another.
Merpati 152, turn left heading 2-4-0 to intercept runway zero Number one always lags behind a bit so keep an eye on it for me.
The mix-up means the crew of flight 152 never hear a critical instruction to approach the runway from the right side instead of the usual left.
Indonesia 152, say again? The captain compounds the problem when he enters an incorrect altitude into the autopilot.
ATC COMMS: Indonesia 152, traffic clear.
Descend to 2,000ft.
Descending to 2,000ft, Indonesia 152.
The error keeps the autopilot from holding the plane at 2,000ft as the crew expects.
Thick smoke from forest fires obscures the view of landmarks on the ground.
Thinking the runway is to his left, the captain turns away from the airport, towards mountains.
152, confirm you are turning left now.
- We are turning right now.
- 152, OK.
Continue turning left.
In the confusion over the turn, no-one notices that the Airbus is dropping dangerously close to the ground.
Ultimately, the warning that should alert them to the danger never sounds.
What? Come on, climb! Climb! Pull up.
Pull up.
Pull up.
No! No! No! No! No! In their final report, Indonesian investigators call for improved communications training for pilots, as well as upgrades to Medan's radar system.
They also advise against using the same flight number for more than one plane on the same route.
I think what really hit home to me about this accident and the loss of so many lives, was how avoidable it was.
At the end of the investigation, we were surprised that there were so many human errors that happened one after another.
All of these things came together to make an accident very much more likely.
If you took away any one of those factors the accident might not have happened.
Captioned by Ai Media ai-media.
tv
No! No! No! It was the biggest human loss in Indonesian history.
It really was overwhelming.
These are two pieces we need to find.
The task was to find the black box.
As investigators begin to examine the evidence COMMS: Indonesia 152, turn right heading 0-4-6.
Here, right on course.
.
.
each new clue is more perplexing than the last.
- That's go-around power.
- We cannot figure it out.
The impact point was nowhere near where we would expect the aircraft to be.
Where did they think they were going? We just didn't understand that.
## (PACEY MUSIC) NARRATOR: There are 222 passengers on-board Garuda Indonesia flight 152.
They're on their way to the city of Medan on the Indonesian island of Sumatra.
Let's stay on autopilot as long as we can.
Yes, sir.
Captain Rahmo Wiyogo has been flying in Indonesia for nearly 20 years.
He's extremely familiar with today's flight path.
For missed approach, climb straight ahead to 2,500 and contact ATC.
You don't have to write this down.
Just relax.
Yes.
OK, sir.
Tata Zuwaldi has only recently upgraded from flight engineer to first officer.
The plane they're flying is an Airbus A300, one of the most reliable commercial airliners in the sky.
Flight 152 left the Indonesian capital of Jakarta nearly 90 minutes ago.
Headed northwest, it is expected to arrive at its destination in about half an hour.
MALE VOICE: Surface winds calm.
Visibility 400m.
An automatic weather report alerts the crew to one factor about their flight that's not routine.
Present weather - smoke.
Forest fires in Sumatra have sent a thick blanket of smoke across all of Southeast Asia.
It's wreaking havoc on people's health and on air traffic.
Smoke is limiting visibility to a degree that would make the descent and the approach really quite difficult.
Not impossible but really quite difficult.
The cabin crew of Flight 152 begin preparing for the upcoming descent.
On the ground, it's a busy afternoon for Medan air-traffic controllers.
Indonesia 152 requesting descent clearance.
They're handling flights from several domestic airlines, including Merpati, Bouraq and Garuda Indonesia.
Confirming descent to flight level 1-4-0.
The controller clears Garuda 152 to begin its descent.
Descending to flight level 1-4-0, Indonesia 152.
Medan Airport has just one runway.
Right now the controller has a Bouraq Airlines flight ready to take off.
He needs to slow the approaching Garuda flight until that plane clears the runway.
Indonesia 152, descend to 3,000ft for runway 0-5.
Reduce speed 2-2-0.
Reduce speed to 220 knots, Indonesia 152.
Seatbelt.
No smoking.
Less than 15 minutes from the airport, flight 152 descends through 10,000ft.
It's smoky here below 10,000.
Oh, yeah.
The pilot would never have been able to get any external visual cues.
He would have been flying entirely on instruments.
The reduced visibility puts added pressure on the controllers.
If there is smoke all the way down to the ground, the controller knows the pilot is going to encounter problems.
They're gonna need all the help they can get and the controlling should be very accurate.
The captain adjusts the power to his engines.
COMMS:: Merpati 152, turn left heading 2-4-0 to intercept runway 0-5.
Number one always lags behind a bit so keep an eye on it for me.
OK.
Indonesia 152, do you read? Indonesia 152.
Say again? OK.
Ah, turn left heading 2-4-0 2-3-5 now to intercept runway 0-5.
Roger, left heading 2-3-5, Indonesia 152.
The plane below has now taken off.
The runway is clear.
Bouraq 683, turn left heading 1-2-0.
Indonesia 152, traffic clear.
Descend to 2,000ft.
Descending to 2,000ft, Indonesia 152.
If it wasn't for the heavy smoke, passengers would be able to see the ground by now.
They had very limited visibility.
Anybody who's driven a car in fog will know what I'm talking about.
Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
- Flaps 8.
- Speed check.
Flaps 8.
The cockpit is hot.
See what you can do.
It's so hot.
It's set to cool, sir.
It should be fine.
Any second now, the controller expects to see flight 152 turn onto final approach.
What? The Airbus has somehow become dangerously close to the ground.
Come on, climb! Climb! Climb! The crew struggles to raise the plane's nose and gain altitude.
But the 130-tonne jet takes time to respond.
Time they don't have.
No.
No! No! No! No! (BLEEP) Locals rush to the crash site 17 miles from Medan Airport.
It's soon clear there's nothing they can do to help.
All 234 people onboard the flight are dead.
This is the deadliest aviation accident in Indonesia's history.
The entire nation wants answers.
We should come to the answer on not only what happened, how it happened, but also why it happened.
Investigators soon join the throngs of police and locals already at the crash site.
Let's see how far back this wreckage goes.
Santoso Sayogo is a key member of the investigative team, and the accident has affected him personally.
I knew both the captain and first officer for a long, long time.
When you found out that your two friends was the victim of the accident, it's quite a shocking experience.
Santoso! We'll need to secure the site somehow.
The Air Accidents Investigation Branch sends Rob Carter to assist with the investigation.
The site was chaotic.
There were lots of people around, some in uniform but it didn't seem like very many.
There was no overall control.
Lots of people doing different things, very little that seemed to be related to accident investigation.
The smell was almost overpowering at that stage.
Coupled with the heat and the humidity and the pollution it really was overwhelming.
The chaotic scene is an immediate concern for Carter.
He's worried the lack of security could compromise the investigation.
A tremendous number of local people were going over the wreckage in different ways and they were carrying pieces away.
We worried that they might be carrying away bits of aircraft, which we'd be really interested in.
If authorities can't gain control of the site and protect valuable evidence, the truth about what happened to Garuda Indonesia flight 152 may never be known.
OK, good.
- Left engine was found here.
- Excellent.
The wreckage from flight 152 lies 17 miles southwest of Medan Airport.
The compact nature of the crash zone tells investigators that the plane was in one piece when it hit the ground.
It looked as if we had most of, if not all, of the aircraft within an area 120x80m.
That's pretty compact.
The wreckage tells investigators something else as well, something they can't explain.
The debris field shows that the plane was flying away from the airport when it slammed into a hillside southwest of the runway.
It's exactly opposite from the direction they should have been flying.
One of the things that seemed so strange was where the impact point was.
It was nowhere near where we would expect the aircraft to be for the proper sort of approach into the airport.
We just didn't understand that.
These are two pieces we need to find.
They hope the plane's flight recorders can help clear up the mystery.
They should be in this area here.
OK, let's go.
Our principle is find the black box, and the clues and the evidence are there.
Investigators fear the boxes may have been carried off by looters.
They recruit hundreds of local people to search for them.
ROBERT CARTER: We were really looking very strongly for the cockpit voice recorder, flight data recorder, really to fill in any sort of detail on how this had happened.
At the same time, they gather information from the air-traffic controller, the last person to have communicated with flight 152.
They approached from the southeast.
I was trying to bring them in this way, a left turn and a right turn that gets them into runway 0-5.
The controller suspects the captain somehow misinterpreted his instructions and missed the final turn.
He didn't understand which way to turn.
He made a left turn here instead.
But without the cockpit recording and the flight data, it's impossible to say why the plane turned the wrong way.
Perhaps there was a mechanical failure or some other last-minute crisis.
We could not determine why the captain make the aircraft turning to the left.
This is a very interesting.
This is It's a big puzzle.
With no sign of the black boxes, investigators gather air-traffic recordings made in the tower.
It's hoped they can shed some light on why the plane turned away from the airport instead of towards it.
We were still wondering whether it could be some sort of systems failure, possibly even some sort of mild structural failure, some distracting aspect for the pilots.
It really left that pretty wide open.
Roll tape.
COMMS: Confirming descent to flight level 1-4-0.
NARRATOR: The air-traffic recordings capture only the radio calls between the pilots and the controller.
Indonesia 152, descend to 3,000ft for runway 0-5.
They're not as helpful as a CVR recording, which would reveal all sounds and conversation inside the cockpit.
Reduce speed 2-2-0.
He needs to get Bouraq 683 airborne.
But investigators listen closely for any clue as to why the A300 veered so badly off course.
At first, the communication seems completely normal.
Merpati 152, turn left heading 2-4-0 to intercept runway 0-5 from the right side.
But then, the controller uses the wrong call sign.
You have Merpati 152, and now he's got Garuda 152.
Records show that earlier in the day, the controller was talking to a Merpati flight with the same number, 1-5-2.
It seems that now he's mixed up the two call signs.
Instead of Garuda 152, he said 'Merpati 152'.
The Garuda pilot didn't pick this message up for obvious reasons.
- COMMS: Indonesia 152, do you read? - Indonesia 152.
Say again? Then suddenly the controller realised that he'd given the wrong call sign, so he called up for a second time.
OK.
Uh, turn left heading 2-4-0 2-3-5 now to intercept runway 0-5.
Left heading 2-3-5.
Roger, left heading 2-3-5, Indonesia 152.
NARRATOR: It appears the misunderstanding is quickly cleared up.
The controller says they made that turn.
After the brief moment of confusion, the Garuda flight is exactly where it should be.
On heading 2-1-5, Indonesia 152.
That puts them about here, right on course.
One more right turn and he's lined up with the runway.
Indonesia 152, turn right heading 0-4-6.
There it is.
Clear as day.
Turn right heading 0-4-6, Indonesia 152.
OK, stop there.
They definitely understood "Turn right.
" How the flight went so horribly wrong in the final few moments is baffling.
It's in the exact opposite direction they were told.
Why? The ATC give instruction, "Indonesia 152, turn right onto heading 0-4-6," but the aircraft turned to the left.
At that stage, we do not have any clue at all.
Investigators need the CVR if they hope to figure out what exactly went on in the cockpit of Flight 152.
A week after the crash of Garuda Indonesia flight 152, devastating scenes of loss and suffering underscore the accident's human toll.
Indonesians from all walks of life want to know what caused this deadly tragedy.
They have to be somewhere.
Let's go back to where we started and look again.
Let's go.
Come on.
Let's go.
There's still no sign of the plane's black boxes.
Investigators are beginning to worry that the answers so many people are hoping for may never be found.
We've got to find them.
It was very frustrating not having the cockpit voice recorder and the flight data recorder.
They are really crucial to understanding the subtleties of an aircraft accident.
The terrible conditions at the accident site aren't helping.
At that time, it was rainy season and you can imagine how wet it was and slippery, as well.
Despite the setbacks, the team presses on.
Let's see if we can figure out what this plane was doing.
They collect key pieces of wreckage, including flight instruments from the cockpit.
Soerjanto Tjahjono of the National Transportation Safety Committee hopes those instruments will tell him how the plane was performing.
We could not find the black boxes, so we used anything from the cockpit, like the gauges, any instrument in the cockpit.
Many of the gauges on this version of the Airbus are electronic, which means that when they lose power, they display their final readings like a snapshot in time.
When electrical power goes off, the instrument freezes.
Those readings provide valuable insight into the final moments of flight 152.
There it is.
It looks like 1.
552.
That's go-around power.
They were trying to fly out of trouble.
The engine instruments showed us that the engines were actually at a very high level of thrust at the point that they lost electrical power.
The finding reveals that the pilots saw the danger ahead and tried desperately to get their plane to climb.
The crew had responded by increasing the engine thrust when they realised they were close to the ground.
As the evidence begins to add up, the likelihood of a mechanical failure aboard Garuda 152 looks increasingly remote.
It sure seems like the aircraft was under control.
Putting it all together, the instruments seemed to indicate to us that the aircraft was what we call a 'going concern' when it hit that ridge, that it was some sort of controlled flight into terrain.
'Controlled' means that there's nothing wrong with the aeroplane and yet it ploughs into a mountainside.
It's been 26 days since the crash of flight 152.
Investigators still have no explanation for its mysterious final turns and fatal impact.
But then, they get their first big break.
Well, well, well.
It turns out that the plane's voice and data recorders were not carried off by looters, but they were almost completely hidden from sight in the dense Indonesian forest.
It was a surprise for us to find that the two black box were sitting there for 26 days until we found it in very soft soil and entangled with the root of the falling tree.
Let's hope they hold some answers.
They rush the boxes to a lab where technicians will work to recover cockpit sounds and conversation, along with detailed aircraft performance data.
The long wait for the most crucial evidence is almost over.
We tried to concentrate first on the FDR and try to figure out the flight path of the aircraft.
When investigators plot the newly found data, they see that it finally rules out any chance of a mechanical failure.
So left away from the airport and then a right turn smack into the mountains.
It clearly shows that the pilots deliberately commanded that fatal turn.
Where did they think they were going? Can you bring me the descent profile, please? After we got the FDR, some questions got some answers.
The data also shows that the plane was in a steady descent until it hit a treetop at about 1,500ft.
So, why didn't they level off at 2,000ft? Indonesia 152, traffic clear.
Descend to 2,000ft.
The crew was not cleared to descend any lower than 2,000ft.
They should have held that altitude.
So, here we were, somehow, with the aircraft hitting a tree about 500ft below its last cleared altitude.
That was a real mystery.
Investigators now know the pilots turned in a direction opposite to the controller's instructions and dropped below their assigned altitude.
What they still don't know is why.
They hope the cockpit voice recorder can provide an answer.
Let's start with turn number one here.
COMMS: Indonesia 152 requesting descent clearance.
NARRATOR: For Santoso Sayogo, the job of listening to the recording comes with an extra burden.
I knew both pilots, the captain and the first officer, and I personally can recognise whose voice are coming from the CVR.
It's not easy to listening to the tape.
ATC COMMS: Merpati 152, turn left heading 2-4-0 to intercept runway 0-5 from the right side.
OK, that's the confused call sign.
Number one always lags behind a bit so keep an eye on it for me.
OK.
The tape reveals that the Garuda pilots don't respond to the first instruction because they don't think it's for them.
ATC COMMS: Indonesia 152, do you read? Indonesia 152.
Say again? OK.
Uh, turn left heading 2-4-0 2-3-5 now, to intercept runway 0-5.
NARRATOR: The controller repeats himself.
Roger, left heading 2-3-5, Indonesia 152.
The crew then make the turn as instructed.
Why so far out? So far out? And yet, the recording leaves investigators with a disturbing impression.
152, heading 2-3-5.
Confirm that we are clear of the mountainous area.
He doesn't sound sure of where he is.
There seemed to be some degree of confusion between the pilots and the air-traffic controller as to where the aircraft was.
Confirm, sir.
Continue turning left heading 2-1-5.
They're on course.
A right turn toward the runway is next.
ATC COMMS: Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
They turned left instead.
What investigators hear next makes the left turn even more baffling.
- Flaps 8.
- Speed, check.
Flaps 8.
Even though the crew is turning away from the airport, they're configuring their plane as though heading towards it.
Why would you extend flaps while turning away from the airport? What if he thinks he is turning towards the airport? What if he thinks he's here? He believes he has to turn left to get to the runway.
Feeling he may be close to a breakthrough, Santoso Sayogo reviews the airport approach chart.
The charts lay out what the normal approach is, and the pilots normally expect to fly that.
He discovers that Garuda 152 wasn't on the standard approach.
The standard approach to Medan is from the left side, which involves making a final left turn to line up with the runway.
But because there was an aircraft departing, the Garuda captain was instructed to approach from the right side of the runway, requiring something he wasn't used to - a right turn before landing.
The controller took them in a direction, which was not what they would have expected according to the approach charts.
But there shouldn't really have been a problem with that.
Controllers are supposed to confirm the approach path with the pilots well before they get to the runway.
How could he not have known which approach he was flying? Back to 1:27, please.
ATC COMMS: Merpati 152, turn left heading 2-4-0 to intercept runway 0-5 from the right side.
NARRATOR: As Santoso Sayogo listens again to what he thought was a harmless call-sign mix-up, he suddenly realises that it had major consequences.
Indonesia 152, say again? When the controller repeats the approach instructions, he leaves out a critical detail.
Turn left heading 2-4-02-3-5 now, to intercept runway 0-5.
He didn't repeat which side they were approaching from.
He should have made it clear, "You're not going to come in from the left-hand side of the runway.
You're going to come in from the right-hand side.
" He thinks he's flown past the airport when he's told to make this turn.
He's expecting the next turn to be a left turn but instead, he's told to turn right.
It seems that the captain, still unable to see the ground through the smoke, dials in a left turn out of habit.
It is a tragic error that leads to disaster.
But investigators now wonder, "Why did the first officer not notice his captain's mistake?" Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
First Officer Zuwaldi clearly acknowledges the instruction for a right turn.
Yet seconds later, the plane turns left.
It's almost impossible to understand.
Investigators have established that the captain of Garuda Indonesia flight 152 made a fatal turn after a radio-call mix-up left him with a confused mental picture of the approach he was flying.
The vectors, the directions given them by the air-traffic controller, can create a bit of confusion.
Controllers didn't make it clear enough to the pilots that this was not going to be the standard pattern.
ATC COMMS: Indonesia 152, turn right heading 0-4-6.
Turn right heading 0-4-6, Indonesia 152.
NARRATOR: They focus on the words of the first officer in an attempt to understand why he didn't immediately react to the wrong turn.
It's getting hot, isn't it? The cockpit is hot.
See what you can do.
It's so hot! The captain asked the first officer to check the air-conditioning.
The co-pilot turned his eyes upward to the panel where he checked the air-conditioning controls.
The brief distraction diverts the first officer's attention from his instruments at a critical moment.
It's set to cool, sir.
It should be fine.
As a result, the co-pilot missed crucial information from the instruments.
Turn right! He looked back.
He was surprised to find out that the aircraft turning to the left instead turning to the right.
Indonesia 152, confirm turning left or right heading 0-4-6.
ATC COMMS: Turning right, sir.
Sorry, Captain.
Sorry.
Roger, 152.
152, confirm you are turning left now.
We are turning right now.
152, OK.
Continue turning left.
NARRATOR: In all the confusion over which way to turn Turn left? - We are turning right now.
- Oh, god! OK NARRATOR: .
.
valuable seconds are lost.
They're flying straight towards the mountain.
ROBERT CARTER: There were many confusing factors for him.
What? The smoke pollution was certainly one of them.
The confused instructions of air-traffic control.
He did not really have a good mental picture of where the aircraft was and where it was meant to be.
Climb! Climb! Climb! The moment they took the wrong turn, they were doomed.
It was this uncertainty, lack of clarity in the captain's head, which really let this accident happen.
NARRATOR: The recording helps explain how Garuda flight 152 ended up so badly off-course.
But it doesn't answer another critical question.
Indonesia 152, traffic clear.
Descend to 2,000ft.
Descending to 2,000ft, Indonesia 152.
The crew was instructed to descend no lower than 2,000ft and their autopilot should have kept them at that altitude.
They had gone straight through 2,000ft and were heading for 1,500ft, and that was too low.
How did they end up below 2,000ft? Either the autopilot had failed in some way or other, which is unusual, or the crew had input the wrong altitude.
NARRATOR: Unfortunately for investigators, the plane's autopilot system was destroyed in the crash.
This impact was so severe, they could pick up the bits afterwards but they couldn't establish whether there was something wrong with it on the day.
Maintenance records show no history of the autopilot ever failing to maintain proper altitude, so a malfunction seems unlikely.
And a report from Airbus all but eliminates the possibility of autopilot failure.
Engineers calculated that the odds of such a failure are less than one in two billion.
It's almost impossible for it to fail.
Descending to 2,000ft, Indonesia 152.
Investigators suspect the captain made an error while entering his minimum altitude.
It was more probably crew mis-setting than it was autopilot failure.
Indonesia 152, confirm turning left or right heading 0-4-6.
ATC COMMS: Turning right, sir.
Sorry, Captain.
Sorry.
Roger, 152.
As the aircraft passes below its target altitude of 2,000ft ATC COMMS: 152, confirm you are turning left now.
- We are turning right now.
- .
.
the pilots are engaged in a confusing conversation about which direction to turn.
152, OK.
Continue turning left.
Turn left? We're turning right now.
They were so preoccupied with their turn, they didn't notice their altitude.
Both pilots didn't realise that the aircraft already left 2,000ft.
By the time the first officer does notice the dangerously low altitude Uh, we're descending.
What? .
.
it's too late.
The quality of their monitoring of their instruments was not up to scratch.
Come on, climb! Climb! Climb! And that's why they got too low and they hit the high ground.
It's finally clear how Garuda Indonesia flight 152 dropped below the minimum safe altitude.
But there are still important questions to answer.
ATC COMMS: Indonesia 152, traffic clear.
Descend to 2,000ft.
The controller in Medan had a read-out of flight 152's altitude and direction.
If he'd recognised the danger and warned the crew, hundreds of lives could have been saved.
Why didn't that happen? ATC COMMS: Descending to 2,000ft, Indonesia 152.
Investigators need to understand why the Medan controller never warned the Garuda pilots of impending danger.
They pore over the technical specifications for Medan's radar system.
Most advanced radar systems refresh every five seconds.
But they soon discover that the radar in Medan is far from advanced.
The radar only refreshed every 12 seconds.
That means the controller only gets an updated picture of where the aeroplane is every 12 seconds.
152, confirm you are turning left now.
- We are turning right now.
- A lot can happen in 12 seconds.
So when the pilot turned in completely the wrong direction - Continue turning left.
- .
.
the controller was not seeing what the pilot was doing Oh, god.
.
.
until it was getting to be too late.
Investigators are close to fully understanding the tragic crash of flight 152.
There's just one last mystery to solve.
Most commercial jets have a cockpit alarm that sounds when the plane flies too close to terrain.
AUTOMATED VOICE: Terrain.
Terrain.
Pull up.
Pull up.
NARRATOR: It's called the Ground Proximity Warning System, a loud automated voice alerting pilots to danger.
One of the big questions for us was, "Why did the accident happen when the aircraft was equipped with a Ground Proximity Warning System?" According to the flight data recorder, the GPWS on flight 152 was triggered five times.
The crew should have heard the first warning 37 seconds before impact.
But when they check the cockpit recording, they only hear the voice alarm once.
Pull up.
Pull up.
Pull up.
And it comes just four seconds before impact.
Something's not right.
They send the tape to an audio lab where sound technicians enhance the quality of the recording.
Listening to the enhanced tape, investigators make a stunning discovery.
Pull up.
Pull up.
Pull up.
The alert, "Pull up, pull up," is not the sound of an automated voice.
It's definitely Zuwaldi, the first officer.
Then we realised the recorded of, "Pull up, pull up," wasn't from the GPWS but it was from one of my friend.
It can mean only thing.
We knew that the GPWS was not working.
It's ultimately revealed that there is a flaw in the GPWS that prevents a warning from sounding when planes are descending over certain types of mountainous terrain.
The GPWS never give the warning to the pilot.
Over the years, GPWS has saved countless lives.
It was sad in this case that those lives weren't saved, and the modern systems, enhanced GPWS, certainly would have worked way better.
Investigators have finally uncovered the tragic series of events that led to the loss of 234 lives.
It all starts with a controller who confuses one call sign for another.
Merpati 152, turn left heading 2-4-0 to intercept runway zero Number one always lags behind a bit so keep an eye on it for me.
The mix-up means the crew of flight 152 never hear a critical instruction to approach the runway from the right side instead of the usual left.
Indonesia 152, say again? The captain compounds the problem when he enters an incorrect altitude into the autopilot.
ATC COMMS: Indonesia 152, traffic clear.
Descend to 2,000ft.
Descending to 2,000ft, Indonesia 152.
The error keeps the autopilot from holding the plane at 2,000ft as the crew expects.
Thick smoke from forest fires obscures the view of landmarks on the ground.
Thinking the runway is to his left, the captain turns away from the airport, towards mountains.
152, confirm you are turning left now.
- We are turning right now.
- 152, OK.
Continue turning left.
In the confusion over the turn, no-one notices that the Airbus is dropping dangerously close to the ground.
Ultimately, the warning that should alert them to the danger never sounds.
What? Come on, climb! Climb! Pull up.
Pull up.
Pull up.
No! No! No! No! No! In their final report, Indonesian investigators call for improved communications training for pilots, as well as upgrades to Medan's radar system.
They also advise against using the same flight number for more than one plane on the same route.
I think what really hit home to me about this accident and the loss of so many lives, was how avoidable it was.
At the end of the investigation, we were surprised that there were so many human errors that happened one after another.
All of these things came together to make an accident very much more likely.
If you took away any one of those factors the accident might not have happened.
Captioned by Ai Media ai-media.
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